Method of cooling gases



April 11, 1939. J. SCHIERENBECK 2,153,644

METHOD OF COOLING GASES Filed Sept. 30, 1936 GAS TO BE COOLED d r r N -l U e \SPE/VT COOL/NG GAS AND VAPOR i q c COOLING 6A6 FOAM COOLING LIQUID x x.

Jaime? Sch L'erenbeO/V INVENTOR i M ATTORNE s Patented Apr. 11, 1939 I I UNITED STATES PATENT OFFICE METHOD OF COOLING GASES- Julius Schierenbeck, Heidelberg, Germany, assignor to I. G. Farbenindustrie Aktiengescllschaft, Frankfort-on-the-Main', Germany Application September 30, 1936, Serial No. 103,258

In Germany October 11, 1935 3 Claims. (Cl. 62176) The present invention relates to a method of foam. In this way the heat of condensation set cooling gases, in particular to the cooling of gases free at any point of the cooling surface that is having a high content of water vapor. in contact with the foam may be immediately The cooling of hot gases having a high conutilized to evaporate cooling liquid from the liq- 5 tent of water vapor offers considerable difliculty uid film into the cooling gas enclosed within because it is necessary to withdraw the great heat the foam. Since with a foam the single films of condensation of the Water vapor at the moment surrounding the gas bubbles are in direct conof condensation and this has only hitherto been tact with each other a good heat-transfer is effected by the use of extremely large amounts effected from film to film over the whole foam m of cooling liquid. Thus'for example in the conand consequently even those films and the gas 1 version of carbon monoxide intohydrogen-conbubbles surrounded by them which are not in taining gases by the use of steam, the cooling direct contact with the cooling surfaces have a of the reacted gas from 150 to 60 C. with the cooling effect on these surfaces. Thus the cosimultaneous condensation of about 250 grams eflicient of transfer of heat on the foam side is of steam per cubic meter of the gas requires, brought up to the value of the transfer coeffi- 15 even with direct cooling, about 10 kilograms of cient on the other side (heat transfer of concooling water per cubic meter of gas. densed ,water vapor), so that very small cooling It has also been. proposedto cool gases consurfaces and very small amounts of cooling water taining water vapor indirectly with mist proare suflicient. As compared with the use of mist duced by spraying water into air. The use of the poor heat-transfer from the cooling surface 20 this mist reduces the amount of cooling liquid to the cooling gas is replaced by the better heatrequired but the resulting cooling action is not transfer to the liquid substance building up the sufficient for many purposes, in particular in the foam. Cooling gas, however, is always present above mentioned conversion of carbon monoxide so that the heat evolved by condensation at any into gases containing hydrogen by the action of place of the hot part of the cooling surface may 5 steam, This is probably due to the fact that be dissipated immediately by evaporation of part the liquid particles suspended in the mist cannot of the foam liquid into the gas bubbles. By be evenly distributed over the cooling surfaces reason of the heating, the bubbles continually and that furthermore only a small portion of expand as they ascend (see the drawing) and the said liquid particles comes into direct conthe thickness of the film of liquid of the single 30 tact with the said surfaces. The heat transfer bubbles thus continually decreases until finally therefore'takes place mainly to the gas carrythe bubbles burst and the non-vaporized portion ing the liquid particles and then from the gas of the film of the bubbles is split up into quite to these particles. In view of the poor heat con a fine mist which ascends and vaporizes. Thus 3 ductivity of gas the heat transfer is consequently in this way the cooling gas, by utilizing the heat not satisfactory. of condensation of the gas to be cooled, may

I have now found that the said difficulties can be saturated with water vapor. In the cooling be overcome by employing a foam of gas and of the hot reacted gases from the reaction deliquid for the indirect cooling of gases of the scribed above, the amount of cooling gas amounts said kind, a fraction only of the amount of for example only to 1/1.3 of the final amount 40 cooling water hitherto used being necessary. The of the gas to be cooled. Since cooling gas is said foam of gas and liquid is produced from continuously made up into a foam with the liqgas other than that which is to be cooled. The uid the gas used up by saturation with evapogas containing water vapor to be cooled flows rated liquid is replaced continuously by the inon one side of a cooling surface, preferably downtroduction of fresh cooling gas. 45 wards, and the cooling foam of gas and liquid The foam of gas and liquid may be produced flows on the other side of the cooling surface, in any suitable manner. For example the gas preferably upwards. and the liquid may be mixed, with or without In this way, on the foam side of the cooling the addition of foaming agents, by stirring appasurface, as far as the foam reaches there are presratus or by means of filter plates through which 5 ent at the same time both cooling water and the gas is forced into the liquid. The most cooling gas. The transfer of heat takes place simple method of producing the foam is that from the cooling surface to the cooling water illustrated in the drawing (representing in a contained in the liquid films of the foam and diagrammatic manner a verticalsection of an thence to the cooling gas enclosed within the apparatus in which the cooling according to the present invention may be carried into practice) by using one or more nozzles in which the discharge end a of inlet pipe for the gas is so screened by a simple deflecting plate b that the gas flows out at great speed, preferably horizontally, The considerable effect of a simple nozzle may be seen from the fact that, for example, by the introduction of cooling gas at a speed of 50 meters per second, the liquid is completely converted into a coherent foam extending from about 10 to 20 centimeters below the nozzle to about 150 centimeters above it. The foaming thus obtained, even without foaming agents, is of such efliciency that the foam produced, for example in the outer chamber of the tubular cooler shown in the drawing, is evenly distributed between the tubes. The gas supply nozzles may also be arranged'laterally between the bundles of tubes and the outer jacket of the tubular cooler without impairing the action.

The nature of the invention will be further described by the following more det riled explanation of the operation of the apparatus shown in the drawing; but it is to be understood that the 2 invention is not restricted to the particular apparatus shown.

Referring to drawing, cooling gas is supplied at c and cooling water at (1, while gas saturated with water vapor, and preheated, leaves at e.

The gas to be cooled enters at f and leaves through the pipe g after flowing through the cooling tubes of the cooler.

With the same cooling surface and the same amount of cooling agent, the amount of water vapor withdrawn by condensation is about'3 to 4 times as great as when the cooling gas is passed through the gas chamber of the tubular cooler without the formation of foam.

The process according to this invention is obviously also capable of use for the cooling of dry gases or of gases having but a slight moisture content. In this case the foam cooling offers the great advantage that the cooling action on the cooling side can be increased to a marked degree whereas increasing the heat transfer example by increasing the speed of the cooling agent is generally impossible in tubular coolers since the area of the space around the tubes is usually very large.

Instead of the cooling surfaces being vertical, they may also be inclined or horizontal.

What I claim is:

l. A process for cooling hot gases which comprises bringing them into indirect heat-exchange relation with a foam of gas and liquid having a lower temperature than the said hot gases, said foam being produced from a liquid and a gas other than the hot gas to be cooled.

2. The process as claimed in claim 1 wherein the foam is produced by passing the gas other than the hot gas to be cooled at a high speed through narrow apertures into the cooling liquid.

3. The process for cooling hot gases which comprises directing a stream of hot gases along a predetermined path having a portion of the path in heat exchanging relation with a liquid and so projecting a stream of cooling gas against said liquid as to cause the formation of foam which foam tends to move in heat exchanging relation and counter current to the stream of hot gases.

' JULIUS SCHIERENBECK.

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